Professor Dragan Poljak from the University of Split in Croatia gave a special seminar at Ashurst Lodge on ‘Transient Modelling of Grounding Electrodes’.

He referred to the importance of the grounding systems for which the principal task was to ensure the safety of personnel and to prevent damage of installations and equipment.

He also referred to the way of calculating the transient impedance of the horizontal and vertical grounding electrodes, as the main parameter in the time domain studies of such systems.

Dragan went on to discuss the analytical transmission line and electromagnetic field approach to the subject based on the wire antenna theory and related integral equation formulation of the problem.

A special concern has been focused on the approach of how to take into account the influence of earth-air interface. Dragan suggested the use of a simplified reflection coefficient instead of a rigorous, but very demanding Sommerfeld integral approach.

Dragan also gave an overview of the applied numerical procedures featuring the Galerkin Bubnov Boundary Element Method.

Finally, he discussed many computational examples for various sets of parameters related to realistic engineering problems.

The Seminar was followed by a lively discussion particularly related to the limits of the reflection coefficient approximation.